1 /*- 2 * SPDX-License-Identifier: BSD-3-Clause 3 * 4 * Copyright (c) 1989, 1993 5 * The Regents of the University of California. All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 3. Neither the name of the University nor the names of its contributors 16 * may be used to endorse or promote products derived from this software 17 * without specific prior written permission. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29 * SUCH DAMAGE. 30 */ 31 32 #include <sys/types.h> 33 #include <sys/stat.h> 34 #include <sys/uio.h> 35 36 #include <dirent.h> 37 #include <errno.h> 38 #include <fcntl.h> 39 #include <paths.h> 40 #include <signal.h> 41 #include <stdbool.h> 42 #include <stdio.h> 43 #include <string.h> 44 #include <stdlib.h> 45 #include <unistd.h> 46 47 #include "ttymsg.h" 48 49 /* 50 * Display the contents of a uio structure on a terminal. If shout is 51 * non-zero, do so even if the terminal has messages disabled. Used by 52 * wall(1), syslogd(8), and talkd(8). Forks and finishes in child if 53 * write would block, waiting up to timeout seconds. Various "normal" 54 * errors are ignored (exclusive-use, lack of permission, etc.). 55 */ 56 int 57 ttymsg(struct iovec *iov, int iovcnt, const char *tty, int timeout, 58 bool shout) 59 { 60 struct iovec localiov[TTYMSG_IOV_MAX]; 61 struct stat sb; 62 ssize_t wret; 63 size_t resid; 64 int cnt, dd, fd, serrno; 65 int forked; 66 67 forked = 0; 68 if (iovcnt > (int)(sizeof(localiov) / sizeof(localiov[0]))) { 69 errno = EFBIG; 70 return (-1); 71 } 72 73 dd = open(_PATH_DEV, O_SEARCH | O_DIRECTORY); 74 if (dd < 0) 75 return (-1); 76 fd = openat(dd, tty, O_WRONLY | O_NONBLOCK | O_RESOLVE_BENEATH); 77 if (fd < 0) { 78 serrno = errno; 79 close(dd); 80 /* 81 * open will fail on slip lines or exclusive-use lines 82 * if not running as root; not an error. 83 */ 84 if (serrno == EBUSY || serrno == EACCES) 85 return (0); 86 errno = serrno; 87 return (-1); 88 } 89 close(dd); 90 if (!shout) { 91 if (fstat(fd, &sb) != 0) { 92 serrno = errno; 93 close(fd); 94 errno = serrno; 95 return (-1); 96 } 97 if ((sb.st_mode & S_IWGRP) == 0) { 98 close(fd); 99 return (0); 100 } 101 } 102 103 for (cnt = 0, resid = 0; cnt < iovcnt; ++cnt) 104 resid += iov[cnt].iov_len; 105 106 do { 107 wret = writev(fd, iov, iovcnt); 108 if (wret >= 0) { 109 resid -= wret; 110 if (iov != localiov) { 111 bcopy(iov, localiov, 112 iovcnt * sizeof(struct iovec)); 113 iov = localiov; 114 } 115 while ((size_t)wret >= iov->iov_len) { 116 wret -= iov->iov_len; 117 ++iov; 118 --iovcnt; 119 } 120 if (wret) { 121 iov->iov_base = (char *)iov->iov_base + wret; 122 iov->iov_len -= wret; 123 } 124 continue; 125 } 126 if (errno == EWOULDBLOCK) { 127 int cpid; 128 129 if (forked) { 130 (void) close(fd); 131 _exit(1); 132 } 133 cpid = fork(); 134 if (cpid < 0) { 135 serrno = errno; 136 (void) close(fd); 137 errno = serrno; 138 return (-1); 139 } 140 if (cpid) { /* parent */ 141 (void) close(fd); 142 return (0); 143 } 144 forked++; 145 /* wait at most timeout seconds */ 146 (void) signal(SIGALRM, SIG_DFL); 147 (void) signal(SIGTERM, SIG_DFL); /* XXX */ 148 (void) sigsetmask(0); 149 (void) alarm((u_int)timeout); 150 (void) fcntl(fd, F_SETFL, 0); /* clear O_NONBLOCK */ 151 continue; 152 } 153 /* 154 * We get ENODEV on a slip line if we're running as root, 155 * and EIO if the line just went away. 156 */ 157 serrno = errno; 158 if (serrno == ENODEV || serrno == EIO) 159 break; 160 (void) close(fd); 161 if (forked) 162 _exit(1); 163 errno = serrno; 164 return (-1); 165 } while (resid > 0); 166 167 (void) close(fd); 168 if (forked) 169 _exit(0); 170 return (0); 171 } 172